This Phase II proposal is submitted as a continuation to Phase I which successfully demonstrated the feasibility of portable high frequency jet ventilation (HFJV). Phase I development has proven the design concept of the HFJV system and demonstrated effective safe operation in a canine experimental model. Sufficient progress and information have been achieved to justify further development of this system. The proposed portable high frequency jet ventilator could be a significant benefit to emergency airway management in the clinical setting. Analysis of the potential market for a portable high frequency jet ventilator reveals several opportunities for sales of large numbers of devices and associated disposables. The second phase of this program continues development of the device to further refine its operation and establish specifications for clinical applications. This involves extensive use of animal experimental models through a consortium arrangement with the Critical Care Department of the University of California, Davis Medical Center. These experiments will result in the accumulation of data necessary for completion of system design as well as justifying subsequent Investigational Device Exemption status and readiness for human clinical testing. Manufacturing and quality assurance methods will be developed to assure the production of hardware suitable for system qualification testing.